Melt-extrusion multiparticulates

ABSTRACT

A unit dose sustained-release oral dosage form containing a plurality of melt-extruded particles, each consisting essentially of a therapeutically active agent, one or more retardants, and an optional water-insoluble binder is disclosed. The particles have a length of from about 0.1 to about 12 mm and can be of varying diameters and each unit dose provides a release of therapeutically active agents over at least about 8 hours. Methods of preparing the unit doses as well as extrusion processes and methods of treatment are also disclosed.

This application is a continuation of Ser. No. 08/334,209 filed Nov. 4,1994 now U.S. Pat. No. 5,965,161.

BACKGROUND OF THE INVENTION

The present invention relates to a process of making granulates ormultiparticulates which are Useful, for example, in pharmaceuticaldosage forms. In particular, the invention relates to a process formelt-extruding pharmaceutical agents with excipients to formmultiparticulates suitable for inclusion in solid dosage forms such ascapsules, tablets and the like.

It is known in the pharmaceutical art to prepare compositions whichprovide for controlled (slow) release of pharmacologically activesubstances contained in the compositions after oral administration tohumans and animals. Such slow release compositions are used to delayabsorption of a medicament until it has reached certain portions of thealimentary tract. Such sustained-release of a medicament in thealimentary tract further maintains a desired concentration of saidmedicament in the blood stream for a longer duration than would occur ifconventional rapid release dosage forms are administered.

Over the years, several different methods of preparing controlledrelease pharmaceutical dosage forms have been suggested. For example,direct compression techniques, wet granulation techniques, encapsulationtechniques and the like have been proposed to deliver pharmaceuticallyactive ingredients to the alimentary tract over extended periods.

Melt granulation techniques have also been suggested to providecontrolled release formulations. Melt granulation usually involvesmechanically working an active ingredient in particulate form with oneor more suitable binders and/or pharmaceutically acceptable excipientsin a mixer until one or more of the binders melts and adheres to thesurface of the particulate, eventually building up granules.

PCT International Publication No. WO 92/06679 discloses melt granulatingmethods for producing pellets containing therapeutically activesubstances. The method includes mechanically working a mixturecontaining the active substance in cohesive form with a binder having amelting point of 40-100° C., while supplying sufficient energy to meltthe binder and form “overmoist” spherical pellets and thereafter addingan additional cohesive substance while maintaining the mechanicalworking to finally produce dry pellets.

PCT International Publication No. WO 93/18753 also discloses anothermelt extrusion process for preparing sustained-release pellets. Thismethod includes pelletizing a mixture containing drug in finely dividedform and a binder which includes one or more water-insoluble-wax-likebinder substances with a melting point above 40° C. using a high shearmixer.

In the spite of the foregoing advances, a need for further alternativesin the field of controlled release formulations has been sought. Thepresent invention addresses this need.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide improvedmethods for producing multiparticulates containing pharmaceuticallyactive ingredients and excipients.

It is a further object of the present invention to providemultiparticulates containing pharmaceutically active ingredients whichdisplay improved controlled-release characteristics.

These objects and others have been accomplished by the presentinvention, which relates in part to a unit dose sustained-release oraldosage form containing a plurality of melt-extruded particles, each ofsaid particles comprising:

a) a therapeutically active agent;

b) one or more retardants; and

c) an optional water-insoluble binder.

The particles have an average length of from about 0.1 to about 12 mmand the unit dose provides a release of the therapeutically active agentover at least about 8 hours.

Another aspect of the invention provides a method of preparing amultiparticulate sustained-release oral dosage form. This methodincludes mixing together a therapeutically effective agent, awater-insoluble retardant and an optional binder to form a homogeneousmixture, heating the mixture and thereafter extruding the mixture intostrands. The strands are then cooled, and reduced to particles having asize of from about 0.1 to about 12 mm. This aspect further includesdividing the particles into unit doses. The ratio of water-insoluberetardant material to therapeutically active agent is sufficient toimpart a release of the active agent from the multiparticulate systemover an extended time period. In this regard, the retardant willcomprise about 5-95% of melt-extruded multi-particulate. Themultiparticulate sustained-release system can be included within a hardgelatin capsule or other oral dosage forms such as a compressed tablet.Methods of preparing such dosage forms are also provided herein.

In yet a further aspect of the invention, there is provided a method oftreating a patient with sustained-release multi-particulate formulationsprepared as described above. This method includes administering a unitdose sustained release oral dosage form containing the novelmelt-extruded particles to a patient in need of the active ingredientcontained therein. For purposes of the present invention, a unit dose isunderstood to contain an effective amount of the therapeutically activeagent.

A still further aspect of the invention provides an alternative methodof preparing a multiparticulate sustained oral dosage form. This aspectincludes directly metering into an extruder a homogeneous mixture of awater-insoluble retardant, a therapeutically active agent, and anoptional binder, heating the homogeneous mixture, extruding said mixtureto form strands, cooling the strands and cutting the strands intoparticles having a size of from about 0.1 to 12 mm and dividing theparticles into unit doses. The ratio of hydrophobic material, namelywater-insoluble retardant (and optional binder) to the therapeuticallyactive agent is sufficient to impart a controlled release of thetherapeutically active agent from the melt-extruded particles and unitdoses over a time period of at least 8 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the inventionand are not meant to limit the scope of the invention as encompassed bythe claims.

FIG. 1 is a graph displaying the dissolution results of Examples 1 and2;

FIG. 2 is a graph displaying the dissolution rates of Examples 3-6;

FIGS. 3 and 4 are graphs displaying the pH dependency of the dissolutionresults of Examples 3, 4 and 6 respectively;

FIG. 4 is a graph displaying the dissolution results of Examples 7 and8;

FIG. 5 is a graph displaying the dissolution results of Examples 6, 7and 8;

FIG. 6 is a graph displaying the dissolution results of Examples 9 and10.

FIG. 7 is a graph displaying the dissolution results of Examples 11 and12;

FIG. 8 is a graph displaying the dissolution results of Examples 15 and16;

FIG. 9 is a schematic representation of a system for carrying out thepresent invention; and

FIG. 10 is a graph displaying the results of Example 5.

DETAILED DESCRIPTION

In accordance with the present invention, there are provided methods forpreparing multiparticulates using melt-extrusion techniques andsustained release oral unit dosage forms containing a plurality of themelt extruded particulates. In accordance therewith, a therapeuticallyactive agent is combined with one or more suitable controlled-releaseretardants, and optionally, a water-insoluble binder, extruded andthereafter rendered into a plurality of melt-extruded particles ormultiparticulates, such as spheres, beads or the like.

Pharmaceutical Agents

The active pharmaceutical agent (s) included in the controlled releasemultiparticulates of the present invention include systemically activetherapeutic agents, locally active therapeutic agents, disinfectingagents, chemical impregnants, cleansing agents, deodorants, fragrances,dyes, animal repellents, insect repellents, a fertilizing agents,pesticides, herbicides, fungicides, and plant growth stimulants, and thelike. The only limitation on the ingredient is that the pharmaceuticalagent is capable of undergoing the inventive extrusion process withoutsubstantially losing its sought-after effect.

A wide variety of therapeutically active agents can be used inconjunction with the present invention. The therapeutically activeagents (e.g. pharmaceutical agents) which may be used in thecompositions of the present invention include both water soluble andwater insoluble drugs. Examples of such therapeutically active agentsinclude antihistamines (e.g., dimenhydrinate, diphenhydramine,chlorpheniramine and dexchlorpheniramine maleate), analgesics (e.g.,aspirin, codeine, morphine, dihydromorphone, oxycodone, etc.),non-steroidal anti-inflammatory agents (e.g., naproxyn, diclofenac,indomethacin, ibuprofen, sulindac), anti-emetics (e.g., metoclopramide),anti-epileptics (e.g., phenytoin, meprobamate and nitrezepam),vasodilators (e.g., nifedipine, papaverine, diltiazem and nicardirine),anti-tussive agents and expectorants (e.g., codeine phosphate),anti-asthmatics (e.g. theophylline), antacids, anti-spasmodics (e.g.atropine, scopolamine), antidiabetics (e.g., insulin), diuretics (e.g.,ethacrynic acid, bendrofluazide), anti-hypotensives (e.g., propranolol,clonidine), antihypertensives (e.g, clonidine, methyldopa),bronchodilators (e.g., albuterol), steroids (e.g., hydrocortisone,triamcinolone, prednisone), antibiotics (e.g., tetracycline),antihemorrhoidals, hypnotics, psychotropics; antidiarrheals, mucolytics,sedatives, decongestants, laxatives, vitamins, stimulants (includingappetite suppressants such as phenylpropanolamine), as well as salts,hydrates, and solvates of the same. The above list is not meant to beexclusive.

In certain preferred embodiments, the multiparticulate systems of thepresent invention include one or more compounds known as opioidanalgesics. Opioid analgesic compounds which may be used in the presentinvention include alfentanil, allylprodine, alphaprodine, anileridine,benzylmorphine, bezitramide, buprenorphine, butorphanol, clonitazene,codeine, cyclazocine, desomorphine, dextromoramide, dezocine,diampromide, dihydrocodeine, dihydromorphine, dimenoxadol,dimepheptanol, dimethylthiambutene, dioxaphetyl butyrate, dipipanone,eptazocine, ethoheptazine, ethylmethylthiambutene, ethylmorphine,etonitazene fentanyl, heroin, hydrocodone, hydromorphone,hydroxypethidine, isomethadone, ketobemidone, levallorphan, levorphanol,levophenacylmorphan, lofentanil, meperidine, meptazinol, metazocine,methadone, metopon, morphine, myrophine, nalbuphine, narceine,nicomorphine, norlevorphanol, normethadone, nalorphine, normorphine,norpipanone, opium, oxycodone, oxymorphone, papaveretum, pentazocine,phenadoxone, phenomorphan, phenazocine, phenoperidine, piminodine,piritramide, propheptazine, promedol, properidine, propiram,propoxyphene, sufentanil, tramadol, tilidine, salts thereof, mixtures ofany of the foregoing, mixed mu-agonists/antagonists, mu-antagonistcombinations, and the like.

In certain particularly preferred embodiments, the opioid analgesic isselected from morphine, codeine, hydromorphine, hydrocodone, oxycodone,dihydrocodeine, dihydromorphine, oxymorphone, hydrates and solvates ofany of the foregoing, mixtures of any of the foregoing, and the like.

Controlled Release Retardants and Binders

According to the present invention, in order to obtain a controlledrelease of the active agent, the therapeutically active agent ishomogeneously combined with a sufficient amount of a release-retardantmaterial and, optionally, a water-insoluble binder prior to undergoingextrusion. The retardant can be a hydrophobic material such as awater-insoluble acrylic polymer or alkylcellulose, or a water solublematerial such as hydroxyalkylcelluloses and related materials. If unitdoses of the multiparticulate are to have about a 12 hour or shorterrelease pattern, hydroxyalkylcelluloses, for example will be extrudedwith the therapeutic agent. If release rates of greater than about 12hours are desired, water-insoluble materials are selected. It is, ofcourse, within the scope of the invention to have particles containingmixtures of the water soluble and insoluble polymers.

In certain preferred embodiments of the present invention, thehydrophobic polymer is a pharmaceutically acceptable acrylic polymer,including but not limited to acrylic acid and methacrylic acidcopolymers, methyl methacrylate copolymers, ethoxyethyl methacrylates,cynaoethyl methacrylate, aminoalkyl methacrylate copolymer, poly(acrylicacid), poly(methacrylic acid), methacrylic acid alkylamide copolymer,poly(methyl methacrylate), poly(methacrylic acid) (anhydride), methylmethacrylate, polymethacrylate, poly(methyl methacrylate), poly(methylmethacrylate) copolymer, polyacrylamide, aminoalkyl methacrylatecopolymer, poly(methacrylic acid anhydride), and glycidyl methacrylatecopolymers.

The melt-extruded particle will comprise from about 1 to about 99% byweight of the retardant and preferably from about 5 to 95% by weight.Other retardant polymers which may be used for the extrusion process ofthe present invention, as those skilled in the art will appreciate,include other cellulosic polymers, including other alkyl cellulosicpolymers, may be substituted for part or all of water-insoluble portionof the retardant in the multiparticulate.

The terms “sustained release” and “extended duration” are defined forpurposes of the present invention as the release of the drug (i.e.,opioid analgesic) at such a rate that blood (e.g., plasma) levels aremaintained within the therapeutic range but below toxic levels over aperiod of time greater than 6 hours, more preferably for periods of upto about 24 hours, or longer.

In certain preferred embodiments, the acrylic polymer is comprised ofone or more ammonio methacrylate copolymers. Ammonio methacrylatecopolymers are well known in the art, and are described in NF XVII asfully polymerized copolymers of acrylic and methacrylic acid esters witha low content of quaternary ammonium groups.

In one preferred embodiment, the acrylic polymer is an acrylic resinlacquer such as that which is commercially available from Rohm Pharmaunder the Tradename Eudragit®. In further preferred embodiments, theacrylic polymer comprises a mixture of two acrylic resin lacquerscommercially available from Rohm Pharma under the Tradenames Eudragit®RL30D and Eudragit® RS30D, respectively. Eudragit® RL30D and Eudragit®RS30D are copolymers of acrylic and methacrylic esters with a lowcontent of quaternary ammonium groups, the molar ratio of ammoniumgroups to the remaining neutral (meth)acrylic esters being 1:20 inEudragit® RL30D and 1:40 in Eudragit® RS30D. The mean molecular weightis about 150,000. Edragit® and Eudragit®L-100 are also preferred. Thecode designations RL (high permeability) and RS (low permeability) referto the permeability properties of these agents. Eudragit® RL/RS mixturesare insoluble in water and in digestive fluids. However,multiparticulate systems formed to include the same are swellable andpermeable in aqueous solutions and digestive fluids.

The polymers described above such as Eudragit® RL/RS may be mixedtogether in any desired ratio in order to ultimately obtain asustained-release formulation having a desirable dissolution profile.Desirable sustained-release multiparticulate systems may be obtained,for instance, from 100% Eudragit® RL, 50% Eudragit® RL and 50% Eudragit®RS, and 10% Eudragit® RL:Eudragit® 90% RS. Of course, one skilled in theart will recognize that other acrylic polymers may also be used, suchas, for example, Eudragit® L.

In other preferred embodiments, the hydrophobic polymer which may beused is a hydrophobic cellulosic material such as ethylcellulose. Thoseskilled in the art will appreciate that other cellulosic polymers,including other alkyl cellulosic polymers, may be substituted for partor all of the ethylcellulose included in the hydrophobic polymer portionof the multiparticulates of the present invention.

In certain preferred embodiments, the release-modifying agent orretardant is selected from materials such as hydroxyalkylcelluloses suchas hydroxypropylmethylcellulose and mixtures of the foregoing.

The retardants may also include a plasticizer. Examples of suitableplasticizers for ethylcellulose include water insoluble plasticizerssuch as dibutyl sebacate, diethyl phthalate, triethyl citrate, tributyl.citrate, and triacetin, although it is possible that otherwater-insoluble plasticizers (such as acetylated monoglycerides,phthalate esters, castor oil, etc.) may be used. Triethyl citrate isespecially preferred.

Examples of suitable plasticizers for the acrylic polymers of thepresent invention include citric acid esters such as triethyl citrate NFXVI, tributyl citrate, dibutyl phthalate, and possibly 1,2-propyleneglycol, polyethylene glycols, propylene glycol, diethyl phthalate,castor oil, and triacetin, although it is possible that otherwater-insoluble plasticizers (such as acetylated monoglycerides,phthalate esters, castor oil, etc.) may be used. Triethyl citrate isespecially preferred.

The binder portion of the melt-extruded particles is optionallyincluded. It has been found that the binder can be reduced or eveneliminated from the extrusion if the physical properties andrelationships between the therapeutically active ingredient andretardant(s) allow a sufficiently cohesive extruded strand to exit theapparatus. A non-limiting list of suitable binders includes hydrogenatedvegetable or castor oil, paraffin, higher aliphatic alcohols, higheraliphatc acids, long chain fatty acids, fatty acid esters, and mixturesthereof.

The binder material may consist of one or more water-insoluble wax-likethermoplastic substances possibly mixed with one or more wax-likethermoplastic substances being less hydrophobic than said one or morewater-insoluble wax-like substances. In order to achieve constantrelease, the individual wax-like substances in the binder materialshould be substantially non-degradable and insoluble in gastrointestinalfluids during the initial release phases.

Useful water-insoluble wax-like substances may be those with awater-solubility that is lower than about 1:5,000 (w/w).

Binder materials are preferably water-insoluble with more or lesspronounced hydrophilic and/or hydrophobic trends. Specifically, thewax-like substance may comprise fatty alcohols, fatty acid esters, fattyacid glycerides (mono-, di-, and tri-glycerides), hydrogenated fats,hydrocarbons, normal waxes, stearic aid, stearyl alcohol and hydrophobicand hydrophilic polymers having hydrocarbon backbones.

In addition to the foregoing, the melt-extruded particles can beprepared to include pharmaceutically acceptable carriers and excipients.It is to be understood that these materials can be mixed with theparticles after extrusion as well. Specific examples of pharmaceuticallyacceptable carriers and excipients that may be used to formulate oraldosage forms are described in the Handbook of Pharmaceutical Excipients,American Pharmaceutical Association (1986), incorporated by referenceherein. Techniques and compositions for making solid oral dosage formsare described in Pharmaceutical Dosage Forms: Tablets (Lieberman,Lachman and Schwartz, editors) Second Edition, published by MarcelDekker, Inc., incorporated by reference herein. Techniques andcompositions for making tablets (compressed and molded), capsules (hardand soft gelatin) and pills are also described in Remington'sPharmaceutical Sciences, (Arthur Osol, editor), 1553-1593 (1980),incorporated by reference herein.

An optional process for preparing the multiparticulates and unit dosesof the present invention includes directly metering into an extruder awater-insoluble retardant, a therapeutically active agent, and anoptional binder; heating said homogenous mixture; extruding saidhomogenous mixture to thereby form strands; cooling said strandscontaining said homogeneous mixture; and cutting said strands intoparticles having a size from about 0.1 mm to about 12 mm; and dividingsaid particles into unit doses. In this aspect of the invention, arelatively continuous manufacturing procedure is realized.

Multiparticulates and Multiparticulate Systems

The multiparticulate system can be, for example, in the form ofgranules, spheroids or pellets depending upon the extruder exit orifice.For purposes of the present invention, the terms “multiparticulate(s)”and “multiparticulate system(s)” and “melt-extruded paricles” shallrefer to a plurality of units, preferably within a range of similar sizeand/or shape and containing one or more active agents and one or moreexcipients, preferably including a retardant as described herein. Inthis regard, the multiparticulates will be of a range of from about 0.1to about 12 mm in length and have a diameter of from about 0.1 to about5 mm. In addition, it is to be understood that the multiparticulates canbe any geometrical shape within this size range such as beads,microspheres, seeds, pellets, etc.

The multiparticulate can thereafter be included in a capsule or in anyother suitable solid form.

The term “unit dose” is defined for purposes of the present invention asthe total amount of substrates needed to administer a desired dose ofdrug (e.g., opioid analgesic) to a patient.

In one especially preferred embodiment, oral dosage forms are preparedto include an effective amount of multiparticulates within a capsule.For example, a plurality of the melt extruded particles may be placed ina gelatin capsule in an amount sufficient to provide an effectivecontrolled-release dose when ingested and contacted by gastric fluid. Incertain preferred embodiments of the present invention, thesustained-release multiparticulate systems are coated with asustained-release coating. The coating formulations of the presentinvention should be capable of producing a strong, continuous film thatis smooth and elegant, capable of supporting pigments and other coatingadditives, non-toxic, inert, and tack-free.

In order to obtain a sustained-release of opioid, for example,sufficient to provide an analgesic effect for the extended durations setforth in the present invention, the melt extruded particles comprisingthe therapeutically active agent may be coated with a sufficient amountof hydrophobic material to obtain a weight gain level from about 2 toabout 30 percent, although the overcoat may be greater depending uponthe physical properties of the particular opioid analgesic compoundutilized and the desired release rate, among other things. In certainpreferred embodiments of the present invention, the hydrophobic polymercomprising the sustained-release coating is a pharmaceuticallyacceptable acrylic polymer, such as those described hereinabove.

The solvent which is used for the hydrophobic material may be anypharmaceutically acceptable solvent, including water, methanol, ethanol,methylene chloride and mixtures thereof. It is preferable however, thatthe coatings be based upon aqueous dispersions of the hydrophobicmaterial.

In one preferred embodiment the multiparticulate is used in asustained-release opioid oral dosage form and includes hydromorphone asthe therapeutically active ingredient in an amount from about 4 to about64 mg hydromorphone hydrochloride. Alternatively, the dosage form maycontain molar equivalent amounts of other hydromorphone salts or of thehydromorphone base. In other preferred embodiments where the opioidanalgesic is other than hydromorphone, the dosage form contains anappropriate amount to provide a substantially equivalent therapeuticeffect. For example, when the opioid analgesic comprises morphine, thesustained-release oral dosage forms of the present invention includeform about 5 mg to about 800 mg morphine, by weight. When the opioidanalgesic comprises oxycodone, the sustained-release oral dosage formsof the present invention include from about 5 mg to about 400 mgoxycodone. In these aspects of the invention, the multiparticulate canbe encapsulated or compressed into solid oral dosage forms furtherinclude combinations of multiparticulates containing one or more of theactive agents disclosed above before being encapsulated. Furthermore,the unit dosage forms can also include an amount of an immediate releaseactive agent for prompt therapeutic effect.

The controlled-release formulations of the present invention slowlyrelease the therapeutically active agent, e.g., when ingested andexposed to gastric fluids, and then to intestinal fluids. Thecontrolled-release profile of the formulations of the invention can bealtered, for example, by varying the amount of retardant, i.e.,hydrophobic polymer, by varying the amount of plasticizer relative tohydrophobic polymer, by the inclusion of additional ingredients orexcipients, by altering the method of manufacture, etc.

For example, hydromorphone-containing multiparticulate may also beovercoated with an aqueous dispersion of the hydrophobic polymer. Theaqueous dispersion of hydrophobic polymer preferably further includes aneffective amount of plasticizer, e.g. triethyl citrate. Pre-formulatedaqueous dispersions of ethylcellulose, such as Aquacoat® or Surelease®,may be used. If Surelease® is used, it is not necessary to separatelyadd a plasticizer. Alternatively, pre-formulated aqueous dispersions ofacrylic polymers such as Eudragit® can be used. These coating solutionsmay also contain film-formers, plasticizers, a solvent system (i.e.,water), a colorant to provide elegance and product distinction. Colormay also be added to or during the extrusion of the therapeuticallyactive agent and retardant.

The plasticized aqueous dispersion of hydrophobic polymer may be appliedonto the multiparticulate comprising the therapeutically active agent byspraying using any suitable spray equipment known in the art. In apreferred method, a Wurster fluidized-bed system is used in which an airjet, injected from underneath, fluidizes the multiparticulate materialand effects drying while the acrylic polymer coating is sprayed on. Asufficient amount of the aqueous dispersion of hydrophobic polymer toobtain a predetermined controlled-release of said therapeutically activeagent when the coated particulate is exposed to aqueous solutions, e.g.gastric fluid, is preferably applied, taking into account the physicalcharacteristics of the therapeutically active agent, the manner ofincorporation of the plasticizer, etc.

In addition to the above ingredients, a controlled-release matrix mayalso contain suitable quantities of other materials, e.g. diluents,lubricants, binders, granulating aids, colorants, flavorants andglidants that are conventional in the pharmaceutical art in amounts upto about 50% by weight of the particulate if desired.

In a further aspect of the present invention, a process for thepreparation of a multiparticulate controlled release, oral dosage formis provided, This aspect includes homogeneously mixing a therapeuticallyeffective agent with a water-insoluble retardant and, optionally, abinder; extruding the mixture, cooling the exiting extruded strands,rendering the strands into particles having a size of from about 0.1 toabout 12 mm in length and optionally, encapsulating or compressing andshaping the granules into tablets. The diameter of the extruder apertureor exit port can also be adjusted to vary the thickness of the extrudedstrands. Furthermore, the exit part of the extruder need not be round;it can be oblong, rectangular, etc. The exiting strands can be reducedto particles using a hot wire cutter, guillotine, etc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 9, a typical melt extrusion systems capable of carryingout the present invention include a suitable extruder drive motor havingvariable speed and constant torque control, start-stop controls, andammeter. In addition, the system will include a temperature controlconsole which includes temperature sensors, cooling means andtemperature indicators throughout the length of the extruder. Inaddition, the system will include an extruder such as twin-screwextruder which consists of two counter-rotating intermeshing screwsenclosed within a cyclinder or barrel having an aperture or die at theexit thereof. The feed materials enter through a feed hopper and ismoved through the barrel by the screws and is forced through the dieinto strands which are thereafter conveyed such as by a continuousmovable belt to allow for cooling and being directed to a pelletizer orother suitable device to render the extruded ropes into themultiparticulate system. The pelletizer can consist of rollers, fixedknife, rotating cutter and the like. Suitable instruments and systemsare available from distributors such as C. W. Brabender Instruments,Inc. of South Hackensack, N.J. Other suitable apparatus will be apparentto those of ordinary skill in the art.

General Pellet Manufacturing Procedure

Premix the required amount of drug, polymers, and optional binder (wax).

Charge a powder feeder with proper amount of drug/excipient blend.

Set temperatures of extruder to the required temperature, depending onthe formulation. Wait until the corresponding heating zones reach steadytemperatures. Start the feeder and the extruder. The drug/excipientpowder blend is melted and intimately mixed in the extruder. Thediameter of the extruder aperture can be adjusted to vary the thicknessof the resulting strand.

Set the conveyor belt speed to an appropriate speed (e.g., 3-100ft/min). Allow the extruded semisolid strand(s) to be congealed andtransported to the pelletizer. Additional cooling devices may be neededto ensure proper congealing. (The conveyor belt may not be needed tocool the strand, if the material congeals rapidly enough.)

Set the roller speed and cutter speed (e.g., to 3-100 ft/min and 100-800rpm). Cut the congealed strands to desired size (e.g., 3-5 mm indiameter, 0.3-5 mm in length).

Collect the pellet product.

Fill a desired weight of pellets into hard gelatin capsules to obtain.an appropriate does of the drug.

Dissolution Method

(USP II Paddle at 100 rpm) 1st hour in 700 ml simulated gastric fluid orSGF thereafter, 900 ml simulated intestinal fluid SIF

Using HPLC procedures for assay

The following examples illustrate various aspects of the presentinvention. They are not meant to be construed to limit the claims in anymanner whatsoever.

EXAMPLES 1-2

In these examples, chlorpheniramine maleate controlled release pelletswere prepared according to the above manufacturing procedure usingethylcellulose and an acrylic polymer (Eudragit RSPO), respectively asthe retardant. The formulations are set forth in Tables 1 and 2 below.The dissolution of these formulations is set forth in FIG. 1. Drugrelease rate from ethylcellulose pellets (prepared at 105° C.) issignificantly slower than that from Eudragit RS pellets (prepared at 85°C).

TABLE 1 EX. 1 Composition Amt. (mg) per Capsule Chlorpheniramine Maleate60 Ethyl Cellulose 84 Stearic Acid 36 Total 180

TABLE 2 EX. 2 Composition Amt. (mg) per Capsule Chlorpheniramine Maleate60 Eudragit RSPO 84 Stearic Acid 36 Total 180

EXAMPLES 3-6 Ex. 3

The excipients used in Ex. 2 were employed to make morphine sulfatecontrolled release pellets. The drug release rate was slower thanexpected especially during later hours of the dissolution.

Ex. 4-6

To increase the drug dissolution rate during later hours, varyingamounts of Eudragit L-100 were incorporated in the formulation. The drugdissolution rate increases with increasing amount of Eudragit L-100 inthe formulation.

TABLE 3 EX. 3 Composition Amt. (mg) per Capsule Morphine Sulfate 60Eudragit RSPO 42 Stearic Acid 18 Total 120

TABLE 4 EX. 4. Composition Amt. (mg) per Capsule Morphine Sulfate 60Eudragit RSPO 38.4 Eudragit L-100 3.6 Stearic Acid 18 Total 120

TABLE 5 EX. 5 Composition Amt. (mg) per Capsule Morphine Sulfate 60Eudragit RSPO 36 Eudragit L-100 6 Stearic Acid 18 Total 120

TABLE 6 EX. 6 Composition Amt. (mg) per capsule Morphine Sulfate 60Eudragit RSPO 33.6 Eudragit L-100 8.4 Stearic Acid (SA) 18 Total 120

As seen in FIG. 3, the drug dissolution rate obtained from the productof Ex. 3 showed a significant pH dependency. The release rate was slowerin SIF (simulated intestinal fluid) than in SGF (simulated gastricfluid).

In FIG. 4, it can be seen that due to the addition of Eudragit L-100,the drug dissolution rate obtained from Ex. 6 was less pH dependent. Thedrug release rate was faster in SIF during later hours of dissolutionwhich is desirable for complete bioavailability.

EXAMPLES 7-8

As demonstrated in FIG. 5, with proper choice of plasticizers, the drugrelease rate from the formula containing Eudragit L-100 can be reduced.This may be necessary to achieve desirable plasma drug concentrationprofiles after oral administration of the pellets.

TABLE 7 EX. 7 Composition Amt. (mg) per Capsule Morphine Sulfate 60Eudragit RSPO 33.6 Eudragit L-100 8.4 Stearic Acid (SA) 9 DiethylPhthalate (DEP) 9 Total 120

TABLE 8 EX. 8 Composition Amt. (mg) per Capsule Morphine Sulfate 60Eudragit RSPO 33.6 Eudragit L-100 8.4 Stearic Acid (SA) 9 TributylCitrate (TBC) 9 Total 120

EXAMPLES 9-10

A different polymer/wax combination was used as an alternativeformulation. As seen in FIG. 6, the drug dissolution rate fromethylcellulose/polyvinyl acetate phthalate was somewhat faster.

TABLE 9 EX. 9 Composition Amt. (mg) per Capsule Morphine Sulfate 60Ethyl Cellulose 38.4 Polyvinyl Acetate Phthalate 3.6 Stearic Acid 18Total 120

TABLE 10 EX. 10 Composition Amt. (mg) per Capsule Morphine Sulfate 60Ethyl Cellulose 34.8 Polyvinyl Acetate Phthalate 7.2 Stearic Acid 18Total 120

EXAMPLES 11-12

The formula used in Ex. 5 was applied to oxycodone hydrochloride. Due tothe higher potency of oxycodone, only 20 mg of drug was used. Themissing 40 mg was replaced by 40 mg of talc (Ex. 12). No replacement wasused in Ex. 11. When tested in only SGF or SIF, the use of Eudragit Lcauses the formulation to become less pH dependent. The results areshown in FIG. 7.

TABLE 11 EX. 11 Composition Amt. (mg) per Capsule OxycodoneHydrochloride 20 Eudragit RSPO 36 Eudragit L-100 6 Stearic Acid 18 Total120

TABLE 12 EX. 12 Composition Amt. (mg) per Capsule OxycodoneHydrochloride 20 Eudragit RSPO 36 Eudragit L-100 6 Stearic Acid 18 Talc40 Total 120

EXAMPLES 13-14 Hydromorphone

The formula used in Ex. 5 was applied to hydromorphone hydrochloride.Due to the higher potency of hydromorphone, only 8 mg of drug was used.The missing 52 mg was replaced by 52 mg of talc (Ex. 14) or 52 mg ofexcipients (Ex. 13). The results are shown in FIG. 8.

TABLE 13 EX. 13 Composition Amt. (mg) per Capsule HydromorphoneHydrochloride 8 Eudragit RSPO 67.2 Eudragit L-100 11.2 Stearic Acid 33.6Total 120

TABLE 14 EX. 14 Composition Amt. (mg) per Capsule HydromorphoneHydrochloride 8 Eudragit RSPO 36 Eudragit L-100 6 Stearic Acid 18 Talc52 Total 120

EXAMPLE 15

In this Example, a bioavailability study was undertaken. Fourteensubjects were given the morphine sulphate formulations of Example 3. Theresults are provided in Table 15 below and in FIG. 10.

TABLE 15 Group AUC C_(max) T_(max) Example 3 Fasted 230 15.7 2.1 Example3 Fed 213 14.0 3.2

From the above data, it can be seen that the formulation is an idealcandidate for an extended release or once-a-day product without a foodeffect.

The examples provided above are not meant to be exclusive. Many othervariations of the present invention would be obvious to those skilled inthe art, and are contemplated to be within the scope of the appendedclaims.

What is claimed is:
 1. A unit dose sustained-release oral dosage formcomprising a plurality of extruded particles, each of said particlescomprising: an opioid analgesic dispersed in a matrix comprising one ormore hydrophobic materials selected from the group consisting of acrylicpolymers and alkylcelluloses; said particles being non-spheroidal andhaving a size from about 0.1 mm to about 12 mm and a diameter from about0.1 mm to about 5 mm, said unit dose providing a release of said opioidanalgesic over at least about 6 hours, said particles being formed bymixing the opioid analgesic and the one or more hydrophobic materials inan extruder to form said matrix, extruding the matrix in the extruder toform strands, and cutting said strands into said extruded particles. 2.A method of treating a patient with a sustained release multiparticulateformulation of a therapeutically active agent, comprising: (a) mixingtogether an opioid analgesic, and a hydrophobic material in an extruderto obtain a homogeneous mixture, the ratio of said hydrophobic materialto said opioid analgesic in said mixture being sufficient to impart arelease of said opioid analgesic from said particles over a time periodof at least about 4 hours when said particle is exposed to an aqueousfluid; (b) heating said homogeneous mixture in the extruder; (c)extruding said homogeneous mixture with the extruder to thereby formstrands; (d) cooling said strands containing said homogeneous mixture;and (e) cutting said strands into particles having a size from about 0.1mm to about 12 mm; and (f) dividing said particles into unit doses; andadministering said unit dose to a patient.
 3. The unit dose of claim 1,wherein said opioid analgesic is selected from the group consisting ofmorphine, codeine, hydromorphone, hydrocodone, oxycodone, oxymorphone,dihydrocodeine, dihydromorphine, pharmaceutically acceptable saltsthereof and mixtures thereof.
 4. The unit dose of claim 1, wherein saidopioid analgesic is selected from the group consisting of alfentanil,allylprodine, alphaprodine, anileridine, benzylmorphine, bezitramide,buprenorphine, butorphanol, clonitazene, codeine, desomorphine,dextromoramide, dezocine, diampromide, dihydrocodeine, dihydromorphine,dimenoxadol, dimepheptanol, dimethylthiambutene, dioxaphetyl butyrate,dipipanone, eptazocine, ethoheptazine, ethylmethylthiambutene,ethylmorphine, etonitazene, fentanyl, heroin, hydrocodone,hydromorphone, hydroxypethidine, isomethadone, ketobemidone,levallorphan, levorphanol, levophenacyl morphan, lofentanil, meperidine,meptazinol, metazocine, methadone, metophon, morphine, myrophine,nalbuphine, narceine, nicomorphine, norlevorphanol, normethadone,nalorphine, normorphine, norpipanone, opium, oxycodone, oxymorphone,papaveretum, pentazocine, phenadoxone, phenomorphan, phenazocine,phenoperidine, piminodine, piritramide, proheptazine, promedol,properidine, propiram, propoxyphene, sufentanil, tramadol, tilidine,pharmaceutically acceptable salts thereof and mixtures thereof.
 5. Thedosage form of claim 3, wherein said opioid analgesic consists of fromabout 2 mg to about 64 mg hydromorphone.
 6. The dosage form of claim 3,wherein said opioid analgesic consists of from about 5 mg to about 800mg morphine.
 7. The dosage form of claim 3, wherein said opioidanalgesic consists of from about 5 mg to about 400 mg oxycodone.
 8. Amethod of preparing a multiparticulate sustained release oral dosageform, comprising: (a) directly metering into an extruder a hydrophobicmaterial and an opioid analgesic; (b) heating said homogeneous mixturein the extruder; (c) extruding said homogeneous mixture with theextruder to thereby form strands; (d) cooling said strands containingsaid homogeneous mixture; and (e) cutting said strands into particleshaving a size of from about 0.1 mm to about 12 mm; and (f) dividing saidparticles into unit doses.
 9. The unit dose of claim 1, wherein saidacrylic polymer is comprised of monomers selected from the groupconsisting of an ester of acrylic acid, an ester of methacrylic acid, analkyl ester of acrylic acid, an alkyl ester of methacrylic acid, andmixtures of any of the foregoing.
 10. The unit dose of claim 1, furthercomprising a water insoluble binder.
 11. The unit dose of claim 10,wherein said binder is selected from the group consisting of stearylalcohol, stearic acid water insoluble waxes, fatty alcohols,hydrogenated fats, fatty acid esters. fatty acid glyercides,hydrocarbons, waxes, and hydrophobic and hydrophilic polymers havinghydrocarbon backbones, and mixtures thereof.
 12. An opioid unit dosesustained-release oral dosage form having substantially nofeeding-fasting effect, comprising a plurality of extruded particles,each of said particles comprising: an opioid analgesic dispersed in amatrix comprising: one or more hydrophobic materials selected from thegroup consisting of acrylic polymers and alkylcelluloses; said particleshaving a size from about 0.1 mm to about 12 mm and a diameter of fromabout 0.1 mm to about 3 mm, said unit dose providing a release of saidopioid analgesic over at least about 12-24 hours, said particles beingformed by mixing the opioid analgesic and the one or more hydrophobicmaterials in an extruder to form said matrix, extruding the matrix inthe extruder to form strands, and cutting said strands into saidextruded particles.
 13. The unit dose of claim 1, wherein each of saidparticles comprise from about,1% to about 99% of said one or morehydrophobic materials.
 14. The unit dose of claim 1, wherein each ofsaid particles comprise from about 5% to about 95% of said one or morehydrophobic materials.
 15. A method of preparing a multiparticulatesustained release oral dosage form, comprising: (a) mixing together anopioid analgesic and one or more hydrophobic materials in an extruder toobtain a homogeneous mixture, the ratio of said one or more hydrophobicmaterials to said opioid analgesic in said mixture being sufficient toimpart a release of said opioid analgesic from said particles over atime period of at least about 4 hours when said particle is exposed toan aqueous fluid; (b) heating said homogeneous mixture in the extruder;(c) extruding said homogeneous mixture with the extruder to thereby formstrands; (d) cooling said strands containing said homogeneous mixture;and (e) cutting said strands into particles having a size from about 0.1mm to about 12 mm; and (f) dividing said particles into unit doses. 16.The method of claim 15, wherein said unit doses are placed into gelatincapsules.
 17. The method of claim 15, wherein said homogenous mixture isheated to a temperature from about 30° C. to about 200° C. prior toextrusion.
 18. The unit dose of claim 1, wherein the diameter of saidparticles is from about 0.1 mm to about 3 cm.
 19. The method of claim15, wherein said opioid analgesic is selected from the group consistingof morphine, codeine, hydromorphone, hydrocodone, oxycodone,oxymorphone, dihydrocodeine, dihydromorphine, pharmaceuticallyacceptable salts thereof and mixtures thereof.
 20. The method of claim15, wherein said opioid analgesic is selected from the group consistingof alfentanil, allylprodine, alphaprodine, anileridine, benzylmorphine,bezitramide, buprenorphine, butorphanol, clonitazene, codeine,desomorphine, dextromoramide, dezocine, diampromide, dihydrocodeine,dihydromorphine, dimenoxadol, dimepheptanol, dimethylthiambutene,dioxaphetyl butyrate, dipipanone, eptazocine, ethoheptazine,ethylmethylthiambutene, ethylmorphine, etonitazene, fentanyl, heroin,hydrocodone, hydromorphone, hydroxypethidine, isomethadone,ketobemidone, levallorphan, levorphanol, levophenacyl morphan,lofentanil, meperidine, meptazinol, metazocine, methadone, metophon,morphine, myrophine, nalbuphine, narceine, nicomorphine, norlevorphanol,normethadone, nalorphine, normorphine, norpipanone, opium, oxycodone,oxymorphone, papaveretum, pentazocine, phenadoxone, phenomorphan,phenazocine, phenoperidine, piminodine, piritramide, proheptazine,promedol, properidine, propiram, propoxyphene, sufentanil, tramadol,tilidine, pharmaceutically acceptable salts thereof and mixturesthereof.
 21. The method of claim 15, wherein said opioid analgesicconsists of from about 2 mg to about 64 mg hydromorphone or apharmaceutically acceptable salt thereof.
 22. The method of claim 15,wherein said opioid analgesic consists of from about 5 mg to about 800mg morphine or a pharmaceutically acceptable salt thereof.
 23. Themethod of claim 15, wherein said opioid analgesic consists of from about5 mg to about 400 mg oxycodone or a pharmaceutically acceptable saltthereof.
 24. A sustained release unit dose formulation comprising theparticles prepared according to the method of claim
 15. 25. The methodof claim 15, wherein at least one of said one or more hydrophobicmaterials is an acrylic polymer comprised of monomers selected from thegroup consisting of an ester of acrylic acid, an ester of methacrylicacid, an alkyl ester of acrylic acid, an alkyl ester of methacrylicacid, and mixtures of any of the foregoing.
 26. The method of claim 15,further comprising mixing a water insoluble binder with said opioidanalgesic and said hydrophobic material in said extruder to obtain ahomogeneous mixture.
 27. The method of claim 26, wherein said binder isselected from the group consisting of stearyl alcohol, stearic acidwater insoluble waxes fatty alcohols. hydrogenated fats, fatty acidesters, fatty acid glycerides, hydrocarbons, waxes, and hydrophobic andhydrophilic polymers having hydrocarbon backbones and mixtures thereof.28. The method of claim 15, further comprising adjusting the apertureand aperture shape of the extruder to obtain a strand having a diameterfrom about 0.1 mm to about 3 cm.
 29. An opioid unit dosesustained-release oral dosage form having substantially nofeeding-fasting effect, comprising a plurality of extruded particles,each of said particles comprising: an opioid analgesic dispersed in amatrix; one or more hydrophobic materials selected from the groupconsisting of acrylic polymers. alkylcelluloses; said particles having asize from about 0.1 mm to about 12 mm and a diameter of from about 0.1mm to about 3 mm, said unit dose providing a release of said opioidanalgesic over at least about 6 hours said particles being formed bymixing the opioid analgesic, and the one or more hydrophobic materialsin an extruder to form said matrix, extruding the matrix in the extruderto form strands, and cutting said strands into said extruded particles.30. The method of claim 2, further comprising mixing a water insolublebinder with said opioid analgesic and said hydrophobic material in saidextruder to obtain a homogeneous mixture.
 31. The method of claim 30,wherein said binder is selected from the group consisting of stearylalcohol, stearic acid, water insoluble waxes, fatty alcohols,hydrogenated fats, fatty acid esters, fatty acid glycerides, hydrophobicand hydrophilic polymers having hydrocarbon backbones and mixturesthereof.
 32. The method of claim 8, further comprising mixing a waterinsoluble binder with said opioid analgesic and said hydrophobicmaterial in said extruder to obtain a homogeneous mixture.
 33. Themethod of claim 32, wherein said binder is selected from the groupconsisting of stearyl alcohol, stearic acid, water insoluble waxes,fatty alcohols, hydrogenated fats, fatty acid esters, fatty acidglycerides, hydrophobic and hydrophilic polymers having hydrocarbonbackbones and mixtures thereof.
 34. The opioid unit dose of claim 12,further comprising a water insoluble binder.
 35. The opioid unit dose ofclaim 34, wherein said binder is selected from the group consisting ofstearyl alcohol, stearic acid, water insoluble waxes, fatty alcohols,hydrogenated fats, fatty acid esters, fatty acid glycerides, hydrophobicand hydrophilic polymers having hydrocarbon backbones and mixturesthereof.
 36. The opioid unit dose of claim 29, further comprising awater insoluble binder.
 37. The opioid unit dose of claim 36, whereinsaid binder is selected from the group consisting of stearyl alcohol,stearic acid, water insoluble waxes, fatty alcohols, hydrogenated fats,fatty acid esters, fatty acid glycerides, hydrophobic and hydrophilicpolymers having hydrocarbon backbones and mixtures thereof.
 38. The unitdose of claim 4 wherein said opioid analgesic is tramadol or apharmaceutically acceptable salt thereof.
 39. The method of claim 20wherein said opioid analgesic is tramadol or a pharmaceuticallyacceptable salt thereof.
 40. The method of claim 2 wherein said opioidanalgesic is tramadol or a pharmaceutically acceptable salt thereof. 41.The method of claim 8 wherein said opioid analgesic is tramadol or apharmaceutically acceptable salt thereof.
 42. The unit dose of claim 12wherein said opioid analgesic is tramadol or a pharmaceuticallyacceptable salt thereof.
 43. The unit dose of claim 29 wherein saidopioid analgesic is tramadol or a pharmaceutically acceptable saltthereof.